I had a big long reply... somehow navigated away and didn't save changes. so here is the pissed off condensed version.
A York OBA will air up tires faster than anything else... by a lot.
Here are some pics;
I got a pressure switch at a place that repairs compressors, the one that is currently in use (not pictured) was taken off a cheapo broken 120v compressor.
Thanks to the low rider crowd these parts have gotten a lot easier to find and cheaper.
Air manifold on front bumper
new air tank 2.5 litters (about all that can fit under a Cherokee)
This is what I am currently running for a tank
http://www.bigrigchromeshop.com/Mer...t_Code=WO806-RT&Product_Count=&Category_Code=
Viar makes some good air tanks
http://www.viaircorp.com/tanks.html
When I initially did the York setup in my bronco I spent less than $200, but I got my York, bracket and tank for free. Fittings get expensive.
I have a switch on the dash that when on provides power to the pressure switch (can be seen in photo of York) the pressure switch comes on when psi is less than 85 and shuts off when psi is greater than 125)
Somewhere you can find out how much oil you are supposed to put in the thing, don't fill it up until you get it mounted and make a dipstick for yourself. (install it empty, put in the 4 oz or whatever of oil, measure it and then you have a dipstick for it)
If I can stuff a York under the hood of an xj with the factory a/c and 2 optima's you should be able to find space for one...
Nathan
Build thread
http://www.rme4x4.com/showthread.php?83436-Nathan-and-Tanja-s-99-XJ-Build-up